Dinoflagellate Cyst Biostratigraphy Research Articles

Organic walled dinoflagellate cyst biostratigraphy of the Bartonian/Priabonian GSSP Alano di Piave section, NE Italy

The present paper augments the multidisciplinary stratigraphic analysis of the Global Stratotype Section and Point (GSSP) Bartonian-Priabonian boundary Alano di Piave section (NE Italy). Twenty-seven stratigraphically signficant organic walled dinoflagellate cyst events, calibrated against the magnetostratigraphic polarity timescale, and earlier established zonations based on calcareous microfossils are recognized. Among these events the first occurrence (FO) of Oligokolpoma agniniae sp. nov. (~8 m below the GSSP boundary), and the FO of Reticulatosphaera actinocoronata (~8 m above the GSSP boundary) may be considered as additional stratigraphic indicators for the Bartonian-Priabonian boundary. Six new potentially stratigraphically significant species Heteraulacacysta alanoensis sp. nov., Heteraulacacysta reticulata sp. nov., Impagidinium bellunoensis sp. nov., Impagidinium veneziaense sp. nov., Lophocysta domenicorioi sp. nov., and Oligokolpoma agniniae sp. nov. are formally described.

Dinoflagellate cyst biostratigraphy of the upper Campanian–lower Maastrichtian interval in the Oslen-Krivodol section, Northwest Bulgaria: preliminary results

A dinoflagellate cyst biostratigraphy for the upper Campanian–lower Maastrichtian interval in the newly described Oslen-Krivodol section, northwest Bulgaria, is proposed. The dinocyst scheme comprises the zones of Areoligera coronata and Cerodinium diebelii, in ascending order, and illustrates the sharp transition between the Campanian and Maastrichtian dinocyst assemblages. The presented results confirm the high potential of dinoflagellate cysts for biostratigraphic correlations in the Campanian–Maastrichtian boundary interval.

Shallow-water hydrothermal venting linked to the Palaeocene–Eocene Thermal Maximum

The Palaeocene–Eocene Thermal Maximum (PETM) was a global warming event of 5–6 °C around 56 million years ago caused by input of carbon into the ocean and atmosphere. Hydrothermal venting of greenhouse gases produced in contact aureoles surrounding magmatic intrusions in the North Atlantic Igneous Province have been proposed to play a key role in the PETM carbon-cycle perturbation, but the precise timing, magnitude and climatic impact of such venting remains uncertain. Here we present seismic data and the results of a five-borehole transect sampling the crater of a hydrothermal vent complex in the Northeast Atlantic. Stable carbon isotope stratigraphy and dinoflagellate cyst biostratigraphy reveal a negative carbon isotope excursion coincident with the appearance of the index taxon Apectodinium augustum in the vent crater, firmly tying the infill to the PETM. The shape of the crater and stratified sediments suggests large-scale explosive gas release during the initial phase of vent formation followed by rapid, but largely undisturbed, diatomite-rich infill. Moreover, we show that these vents erupted in very shallow water across the North Atlantic Igneous Province, such that volatile emissions would have entered the atmosphere almost directly without oxidation to CO2 and at the onset of the PETM.

Late maastrichtian- early eocene dinoflagellate cyst biostratigraphy and aleoenvironmental study of sediments in Akukwa-1 well in the Anambra Basin

Dinoflagellate cyst biostratigraphy and palaeoenvironment of deposition of sediments penetrated by Akukwa-1 Well was carried out with a total of 253ditch cuttings using the conventional maceration technique for recovering of acid insoluble organic-walled microfossils from sediments. Sedimentological description delineated five (5) lithological units within the well, which included those of Nkporo Shale, Mamu Formation, Ajali Sandstone, Nsukka Formation and Imo Shale. A total of 14 genera and 35 species of dinoflagellate cyst were identified. The recovered dinocysts were used to establish palaeoenvironment which ranged from marginal to shallow marine, the forms were also used to propose four (4) informal dinoflagellate cyst zonations labelled (A-D) based on the first and last occurrences of two or more species. They included Zone A (Apectodinium paniculatum zone), occurring at 7990ft(Maastrichtian), zone B(Paleocystodinium australinium zone) occurring between 7990ft -4000ft (Upper Maastrichtian), zone C(Apectodinium homomorphum zone) occurring between 4000ft -2550ft (Upper Maastrichtian), and zone D(Homotryblum palladium zone) occurring between 5550ft-1520ft(Paleocene- Early Eocene). The erected dinocyst zones were correlated with the existing biozones in tropical areas of Africa and northern South America.

Dinoflagellate cyst biostratigraphy of the Bathonian, Callovian, and the Upper Jurassic in North Bulgaria

Forty-four selected organic-walled dinoflagellate cyst species have been used for biozonation of the Bathonian, Callovian, and the Upper Jurassic in North Bulgaria. The dinocysts were collected from 49 borehole sections and two exposures. The following dinocyst zones are herein introduced and described: Lithodinium valensii–Gongylodinium erymnoteichos Concurrent-range Zone (lower–middle Bathonian); Ellipsoidictyon reticulatum Assemblage Zone (upper Bathonian–lower Callovian); Dingodinium harsveldtii Taxon-range Zone (middle–upper Callovian); Lambodinium absidatum Assemblage Zone (lower Oxfordian); Scriniodinium dictyotum papillatum–Caddasphaera halosa Concurrent-range Zone (middle–upper Oxfordian); Rhyncodiniopsis gongylos Assemblage Zone (lower Kimmeridgian); Systematophora varispinosa–Gonyaulacysta? crassicornuta Concurrent-range Zone (middle–upper Kimmeridgian); Edmontodinium polyplacophorum Assemblage Zone (lower Tithonian); and Leptodinium? plagatum–Prolixosphaeridium perforospineum Concurrent-range Zone (middle–upper Tithonian). Some of the zones were partly or completely subdivided in subzones. The dinocyst zones and subzones were correlated with the Bulgarian ammonite and calpionellid zones and subzones.

DINOSTRAT: a global database of the stratigraphic and paleolatitudinal distribution of Mesozoic–Cenozoic organic-walled dinoflagellate cysts

Abstract. Mesozoic–Cenozoic organic-walled dinoflagellate cyst (dinocyst) biostratigraphy is a crucial tool for relative and numerical age control in complex ancient sedimentary systems. However, stratigraphic ranges of dinocysts are found to be strongly diachronous geographically. A global compilation of state-of-the-art calibrated regional stratigraphic ranges could assist in quantifying regional differences and evaluating underlying causes. For this reason, DINOSTRAT is here introduced – an open-source, iterative, community-fed database intended to house all regional chronostratigraphic calibrations of dinocyst events (https://github.com/bijlpeter83/DINOSTRAT.git, last access: 1 February 2022​​​​​​​) (DOI – https://doi.org/10.5281/zenodo.5772616, Bijl, 2021). DINOSTRAT version 1.0 includes >8500 entries of the first and last occurrences (collectively called “events”) of >1900 dinocyst taxa and their absolute ties to the chronostratigraphic timescale of Gradstein et al. (2012). Entries are derived from 199 publications and 188 sedimentary sections. DINOSTRAT interpolates paleolatitudes of regional dinocyst events, allowing evaluation of the paleolatitudinal variability in dinocyst event ages. DINOSTRAT allows for open accessibility and searchability, based on region, age and taxon. This paper presents a selection of the data in DINOSTRAT: (1) the (paleo)latitudinal spread and evolutionary history of modern dinocyst species, (2) the evolutionary patterns and paleolatitudinal spread of dinocyst (sub)families, and (3) a selection of key dinocyst events which are particularly synchronous. Although several dinocysts show – at the resolution of their calibration – quasi-synchronous event ages, in fact many species have remarkable diachroneity. DINOSTRAT provides the data storage approach by which the community can now start to relate diachroneity to (1) inadequate ties to chronostratigraphic timescales, (2) complications in taxonomic concepts, and (3) ocean connectivity and/or the affinities of taxa to environmental conditions.

Dinoflagellate cyst biostratigraphy of initial Neotethys transgression deposits from the Cenomanian and Turonian in the Tarim Basin, western China

Under the great transgressions of the Late Cretaceous, the Neotethys Sea firstly invaded the western Tarim Basin, center Asian and this continued until the Paleogene. This study presents successive dinoflagellate cyst (dinocyst) records from the Kukebai Formaion deposited during initial transgressive periods. A total of 45 samples from the Core ZK 5-2 drilled in the southern part of the western Tarim Basin yield 78 taxa including 74 taxa of dinocysts, two genera of chlorophyte algae, and two acritarch species. Upwardly, three dinoflagellate zones are distinguished in the Kukebai Formation: Subtilisphaera perlucida (interval Zone), Cyclonephelium brevispinatum (interval zone), and Heterosphaeridium difficile (interval zone) respectively. Successive dinocyst records in this study calibrate the chronostratigraphy of the Kukebai Formation from the lower Cenomanian to the lowermost Turonian. A high abundance of Subtilisphaera perlucida and sporadic Litosphaeridium siphoniphorum can be observed in the lowest Kukebai Formation, probably indicating initial sea transgression in the Tarim Basin that took place in early Cenomanian. The distribution events of key dinocyst taxa such as the first occurrence of the H. difficile and the last occurrence of consistent occurrence of Litosphaeridium siphoniphorum, indicate that the C/T boundary interval should be approximately 183 m deep in Core ZK 5–2, at the uppermost Middle Kukebai Formation.

Santonian‐Campanian dinoflagellate cyst biostratigraphy and paleoenvironment of the Krishna‐Godavari Basin, India

AbstractThe present study deals with the biostratigraphic framework of Late Cretaceous sediments of the subsurface Well (DNG) “A” (2085–1840 m depth) from the Raghavapuram/Chintalapalli Shale of the Krishna‐Godavari Basin and analyzed the palynological assemblage. The recorded palynological assemblage is dominated by marker dinoflagellate cyst viz. Areoligera coronata, Areoligera senonensis, Heterosphaeridium spinaconjunctum, Nelsoniella aceras, Nelsoniella semireticulata, Odontochitina porifera, Xenascus ceratioides, and Xenascus gochtii species. The last occurrence (LO) of significant species of dinoflagellate cysts is considered for the biostratigraphic establishment. On the basis of dinoflagellate cyst biostratigraphy, the examined sequences correspond to the Santonian‐Campanian age. The dominance of gonyaulacoid dinoflagellate cysts is interpreted in terms of sea‐level fluctuation and other paleoenvironmental signals through this biostratigraphic establishment. The recorded dinoflagellate cysts indicate the outer neritic, cool depositional environment. The sea‐level rise, recorded in our study is linked with the transgressive phase during the Late Cretaceous (Santonian‐Campanian) period.

Campanian-Eocene dinoflagellate cyst biostratigraphy in the Southern Andean foreland basin: Implications for Drake Passage throughflow

The tectonic opening of the Tasmanian Gateway and Drake Passage represented crucial geographic requirements for the Cenozoic development of the Antarctic Circumpolar Current (ACC). Particularly the tectonic complexity of Drake Passage has hampered the exact dating of the opening and deepening phases, and the consequential onset of throughflow of the ACC. One of the obstacles is putting key regional tectonic events, recorded in southern Patagonian sediments, in absolute time. For that purpose, we have collected Campanian-Eocene sediment samples from the Chilean sector of Southern Patagonia. Using U-Pb radiometric dating on zircons and dinoflagellate cyst biostratigraphy, we updated age constraints for the sedimentary formations, and the hiatuses in between. Thick sedimentary packages of shallow-marine and continental sediments were deposited in the foreland basin during the early Campanian, mid-Paleocene, the Paleocene-Eocene boundary interval and the middle Eocene, which represent phases of increased foreland subsidence. We interpret regional sedimentary hiatuses spanning the late Campanian, early-to mid-Paleocene, mid-Eocene and latest Eocene-early Oligocene to indicate times of reduced foreland subsidence, relative to sediment supply. We relate these changes to varying subduction rates and Andean orogeny. Dinoflagellate cyst assemblages suggest that the region was under the influence of the Antarctic-derived waters through the western boundary current of the Subpolar Gyre, developed in the southwest Atlantic Ocean and thus argues for limited throughflow through the Drake Passage until at least the latest Eocene. However, the proliferation of dinoflagellate endemism we record in the southwest Atlantic is coeval with that in the southwest Pacific, and on a species level, dinoflagellate cyst assemblages are the same in these two regions. This suggests that both regions were oceanographically connected throughout the early Paleogene, likely through a shallow opening of a restricted Drake Passage. This implies a continuous surface-water connection between the south Pacific and the South Atlantic throughout the late Cretaceous-early Paleogene.

Dinoflagellate cyst biostratigraphy of Upper Cretaceous turbiditic deposits from a part of the Bąkowiec section in the Skole Nappe (Outer Carpathians, southern Poland)

Dinoflagellate cysts from turbiditic deposits of the Ropianka Formation in an interval of the Bąkowiec section (Skole Nappe, Outer Carpathians, southern Poland) have been analyzed. This interval, previously attributed to the Cretaceous–Paleogene boundary transition based on planktic and benthic foraminifera, contains organic-walled dinoflagellate cysts (dinocysts) of a latest Campanian age. The difference in age, revealed here between foraminifera and dinocyst findings, is considered as an unresolved dilemma, which is pending some explanations, probably on the basis of further multidisciplinary studies envisaged in the same outcrop. The palynological content is well preserved and rich in dinocyst cyst taxa, including 37 upper Campanian index species among 92 species in total. The dinocyst assemblages observed in this interval are similar to those previously recognized in biostratigraphically well-calibrated sections of Western Europe. The dinocyst marker events enabled a correlation of the studied interval with the Samlandia mayi dinocyst Zone of Slimani (2001a), which is an equivalent to the Belemnitella minor Zone in the northwestern Europe. These dinocyst events include the first occurrences (FOs) of Kleithriasphaeridium truncatum, Nematosphaeropsi philippotii, Samlandia carnarvonensis, Samlandia mayi and last occurrences (LOs) of Corradinisphaeridium horridum, Raetiadinium truncigerum, Odontochitina operculata and Xenascus ceratioides subsp. ceratioides. The palynological content shows significant reworking of Campanian dinocyst taxa and a richness in palynodebris of continental origin, which are likely related to deposition by turbiditic currents.

Cretaceous dinoflagellate cyst biostratigraphy in the Facai-1 well of the Tenere Graben in eastern Niger, Africa

Sixty-five genera and 115 species of dinoflagellate cysts were discovered in the samples from the depth of 600–2652 m in the Facai-1 Well in the Tenere Graben of Niger, Africa. The low diversity and abundance in each single sample make it difficult to divide the dinoflagellate cyst assemblage into biozones. The dinoflagellate cyst assemblage is indicative of a Late Cretaceous age and suggests an abnormal neritic palaeoenvironment.

Organic-walled dinoflagellate cyst biostratigraphy of the upper Eocene to lower Oligocene Yazoo Formation, US Gulf Coast

Abstract. New data from a continuously cored succession, the Mossy Grove core, near Jackson, central Mississippi, recovered ∼137 m of marine clays (Yazoo Formation), spanning ∼5 Ma and including the critical Eocene–Oligocene transition (EOT) event. These clay-rich sediments yield well-preserved calcareous microfossil and palynomorph assemblages. Here, we present a new organic-walled dinoflagellate cyst (dinocyst) biostratigraphic framework, including the recognition of 23 dinocyst bioevents. These are integrated with new age constraints based on calcareous nannofossil biostratigraphy and a reassessment of the existing radiometric dates and planktonic foraminiferal biostratigraphy, permitting the establishment of a robust and significantly refined age model for the core. According to this new age model, a major increase in sedimentation rate – from ∼2.1 to ∼4.7 cm kyr−1 – is observed at a core depth of ∼89.1 m (∼34.4 Ma). In the new age model the section is significantly older than previously thought, by up to 1 Ma, with the Eocene-Oligocene boundary (∼33.89 Ma) placed ∼34 m below the level previously identified. With these more accurate age estimates, future isotopic and palaeoecological work on this core can be more precisely integrated with other, globally distributed records of the EOT.

Bartonian to Priabonian dinoflagellate cyst biostratigraphy and paleoenvironments of the M'karcha section in the Southern Tethys margin (Rif Chain, Northern Morocco)

Abstract Palynological analyses were performed on the Eocene sediments of the M'karcha section, which is located in the Taza region, structural Tsoul Unit, eastern External Rif (northeastern Morocco). The palynological content of this section is composed essentially of well-preserved and diverse dinoflagellate cyst assemblages, allowing detailed taxonomic determinations, age assignments, biostratigraphic correlations and paleoenvironmental interpretations. Other palynomorphs, such as spores, pollen grains and foraminiferal linings, are rare and therefore, not taxonomically determined up to the genus level. 131 dinoflagellate cyst species were identified. Age assignments are based on dinocyst bioevents, considered previously as potential biostratigraphic markers of the Bartonian and Priabonian, including the lowest occurrences (LOs) of Glaphyrocysta semitecta, Impagidinium dispertitum, Rhombodinium perforatum, Cooksonidium capricornum, Stoveracysta ornata, Stoveracysta sp. 2 of Brinkhuis and Biffi (1993) and LO and highest occurrence (HO) of Schematophora speciosa. The quantitative palynological analyses, based mainly on dinoflagellate cysts through the M'karcha section revealed an inner neritic, generally lagoon, environment with a low productivity, alternated with short episodes of the open marine influence.

Dinoflagellate cyst biostratigraphy of the Santonian-Oligocene succession of the Drazia-1 well, North Western Desert, Egypt

The palynological and biostratigraphical studies have been carried out on 59 subsurface cutting samples from three formations (Khoman, Apollonia and Dabaa) represent the Santonian-Oligocene succession of the Drazia-1 well in East Yidma oil field (north Western Desert, Egypt). A total of 115 dinoflagellate cysts species have been identified and utilized in distinguishing five interval dinoflagellate cyst zones for the first time in the Western Desert from old to young: 1) Odontochitina operculata (Santonian-Campanian), 2) Cerodinium diebelii (Maastrichtian), 3) Danea californica (Danian-Selandian), 4) Apectodinium homomorphum (Thanetian–Bartonian), and 5) Deflandrea phosphoritica (Priabonian-Chattian). The established palynozones have been correlated with equivalent Late Cretaceous-Paleogene dinocyst biozones in Egypt and worldwide.

Dinoflagellate cyst biostratigraphy and palaeoecology of the early Paleogene Landana reference section, Cabinda Province, Angola

Forty-four rock samples from the Landana section, belonging to the historical Dartevelle collection of the Royal Museum for Central Africa (RMCA) at Tervuren, Belgium, were palynologically processed and analysed. Systematic analysis of the samples from the Landana sea cliff locality has revealed 90 dinoflagellate cyst taxa spanning an interval that ranges at least from the middle Paleocene to the late Eocene/early Oligocene. This locality represents the first extensive sub-equatorial African Paleogene dinoflagellate cyst record. Dinoflagellate cyst occurrences were calibrated and evaluated against newly revised foraminiferal ranges. This novel dinoflagellate cyst biostratigraphic record was compared and correlated with contemporaneous records relatively close by in the Gulf of Guinea, as well as with records from more distant locations such as Antarctica, Australia and New Zealand. A preliminary dinoflagellate cyst zonation is here proposed comprising three zones and five unzoned yet otherwise distinct intervals. The lower part of the Landana section records a large portion of the early to middle/late Selandian, which is made apparent by the presence of taxa such as Isabelidinium cingulatum, Isabelidinium? viborgense, and Spinidinium densispinatum. The Thanetian through Lutetian part of the section is more fragmentary and is devoid of any significant marker taxa normally typical for this time interval elsewhere. The upper part of the record is largely devoid of dinoflagellate cysts, with the few dinoflagellate cyst-bearing samples pointing to an Eocene to early Oligocene age. Dinoflagellate cyst assemblages are relatively variable and often largely dominated by a single particular taxon or complex. We record remarkably abundant peridinioid cysts signalling high palaeoproductivity for protracted periods of time, resulting from either heightened terrestrial influence or enhanced upwelling.

„Depositional setting of the Oligocene sequence of the Western Carpathians in the Polish Spisz region – a reinterpretation based on integrated palynofacies and sedimentological analyses” – Discussion

In their recent paper, Filipek et al. (2017) provided some data on age (dinoflagellate cyst biostratigraphy) and sedimentary setting (sedimentological and palynofacial analysis) of the Podhale Flysch (Central Carpathian Paleogene) from the Polish Spisz (their fig. 1). They carried out their integrated studies on the middle part of the Podhale Flysch succession – the upper part of the Szaflary beds through the lower part of the Chocholow beds. These studies, as stated in Introduction, “…allow for a new approach to the knowledge on the CCPB with regard to stratigraphy, depositional palaeoenvironment, and changes during deposition”. Authors accented the inconsistency of some of previous studies (biostratigraphical in particular), which provoked them to undertake their studies in order to reinterpret the depositional setting. In my opinion, however, it is hardly possible to find new reinterpretations, and those presented are frequently based on erroneous, commonly random and not complete data and interpretations; none of them are compared nor discussed with previous results. Below, these controversies are briefly presented.

Middle Eocene to early Oligocene dinoflagellate cyst biostratigraphy and paleoenvironmental interpretations of the Ben Attaya section at Taza, eastern External Rif, Morocco

The palynological study was carried out on middle Eocene to early Oligocene sediments from the Ben Aattaya section, located in the Taza region, eastern External Rif, northeastern Morocco. The palynological content is dominated by dinoflagellate cysts (dinocyst), while spores and pollen are rare. Very known dinocyst event markers were used for dating the Ben Attaya section. The first occurrences (FO) of Cerebrocysta bartonensis, Glaphyrocysta semitecta, Lentinia serrata, Operculodinium divergens indicate the Bartonian. The FOs of Deflandrea heterophlycta, Schematophora speciosa, Stoveracysta ornata were used to recognize the Priabonian. While the FOs of Chiropteridium lobospinosum and Wetzeliella gochtii, as well as the last occurrences (LO) of Achilleodinium biformoides, Charlesdowniea coleothrypta subsp. coleothrypta, Enneadocysta pectiniformis, Glaphyrocyst semitecta, Hemiplacophora semilunifera, Lentinia serrata, Operculodinium divergens, Rhombodinium perforatum, Schematophora speciosa and Stoverocysta ornata highlight the Rupelian. The changes in relative abundances of selected dinocyst groups and sporomorphs (pollen and spores) suggest a lagoonal to coastal inner neritic marine environment during the Bartonian and Priabonian, which was interrupted by a short phase of outer neritic conditions at the basal part of the section and ended by a marked decrease in the sea level, probably due to a regression during the Priabonian. The Rupelian deposits indicate a middle neritic marine environment marked by a progressive rise during the transgression.

Low-latitude vegetation and climate dynamics at the Paleocene-Eocene transition – A study based on multiple proxies from the Jathang section in northeastern India

We present a multi-proxy study of an upper Paleocene-lower Eocene succession from the paleo-equatorial region. The study is carried out on a coal-bearing, shallow-marine succession exposed at Jathang, east Khasi hills, Meghalaya, northeastern India. The succession was deposited in a low-energy, coastal marsh-bay complex. Dinoflagellate cyst biostratigraphy yields a late Paleocene to early Eocene age for the section. The deposits of the lower part of the succession represent a transgressive systems tract (TST) defined by seven parasequences, each starting with bay sediments deposited during transgression, followed by a shallowing-upward bay fill-marsh deposit. In the vertical succession, each parasequence acquires an increasingly marine character, culminating in a maximum flooding surface at the Paleocene-Eocene boundary. It is followed by four shallowing upward parasequences deposited in a highstand systems tract (HST). Enhanced chemical weathering and high terrestrial supply are testified by raised SiO2 and Al2O3 contents and high percentages of terrestrial palynomorphs. The pollen flora recovered from the Jathang section was used for quantitative paleoclimate and vegetation reconstructions. The Coexistence Approach was applied based on Nearest Living Relatives (NLRs) of sixty fossil species recorded at different stratigraphic levels. Seven climate variables were determined for the fossil assemblages, and, as a measure of the seasonality of climate, the number of dry months was estimated. Our study shows that during the Paleocene there existed warm, seasonally dry tropical climate conditions with mean annual temperature at ca. 24–26 °C and mean annual precipitation at ca. 700–1800 mm, and with a dry season of 5–6 months. Particularly warm and wet, perhumid climate conditions with 26–27 °C and 2200–3200 mm mean annual precipitation with a dry period of 2–3 months were reconstructed for the latest Paleocene-earliest Eocene interval. The study shows a distinct vegetational turnover from palm-dominated, seasonally dry tropical forest during the Paleocene to highly diversified dicotyledonous megathermal rainforest during the latest Paleocene-early Eocene. The present study demonstrates that the reduced duration of the dry period during the latest Paleocene-earliest Eocene, due to a more active hydrological cycle, played a major role in determining the climate and shaping the vegetation cover in the paleo-equatorial region. There is evidence from our data that seasonality of rainfall is the determining factor for the tropical forest vegetation pattern of the equatorial region rather than mean annual rainfall condition. As the main trigger for the observed step-wise changes of the hydrology along the studied succession, the fast northward movement of the Indian Plate is inferred.

Late Paleogene-early Neogene dinoflagellate cyst biostratigraphy of the eastern Equatorial Atlantic

Six dinoflagellate cyst biozones (zone 1-zone 5, subzones 1a and 1b) are recognized in the late Paleogene-early Neogene interval of the Ocean Drilling Program (ODP) Site 959 (Hole 959 A), Côte d’Ivoire-Ghana Transform Margin in the eastern Equatorial Atlantic. The biozones are based on palynological analysis of 30 samples covering a 273.2-m interval with generally fair preservation and good to poor recovery. We propose a new age of Late Eocene (Priabonian) for subunit IIB as opposed to the previously published mid-Early Oligocene age (middle Rupelian). This age assignment is mainly based on the presence of Late Eocene marker taxa, such as Hemiplacophora semilunifera and Schematophora speciosa in the lower part of the studied interval. We also document for the first time a hiatus event within dinoflagellate cyst zone 3, based on the last occurrences of several taxa. This interval is assigned to an Early Miocene age and is barren of other microfossils. Furthermore, we propose new last occurrences for two species. The last occurrence of Cerebrocysta bartonensis is observed in the late Aquitanian-early Burdigalian in this study vs. Priabonian-early Rupelian in mid and high latitude regions. Also, the last occurrence of Chiropteridium galea extends to the latest Early Miocene (Burdigalian) in ODP Hole 959 A; this event was previously identified in other studies as Chattian in equatorial regions, and Aquitanian in the Northern Hemisphere mid-latitudes. We suspect that these differences are due to physical (offshore vs. nearshore) and latitudinal locations of the areas studied.

Dinoflagellate cyst biostratigraphy of Miocene strata in the Adana Basin, Eastern Mediterranean, Turkey

ABSTRACTThe Adana Basin is one of the major Neogene basins situated in SW Turkey with sedimentary successions providing good records of the paleoenvironmental changes that affected the Mediterranean area. Since a detailed biochronostratigraphic framework has not been properly established in the Adana Basin yet, this study will be the first multidisciplinary approach carried out in this region. In addition, a detailed biozonation based on marine palynomorphs was the first ever documented from the Köpekli Formation deposited during the Miocene (from late Burdigalian to Langhian) and the established biozones were correlated with those of planktonic foraminifera and calcareous nannofossils. According to the first occurrences (FOs) and the last occurrences (LOs) of selected taxa, five biozones (P-1, P-2, P-3, P-4 and P-5) based on dinoflagellate cysts; five biozones (M4a, M4b, M5a, M5b and M6) based on planktonic foraminifera; and two biozones (NN4 and NN5) based on calcareous nannofossils were established in the Miocene Köpekli Formation. In order to achieve a worldwide biostratigraphic perspective based on dinoflagellate cysts, the present biozones were compared with those described from NW Europe (Denmark, Germany, the Netherlands), the East Coast of the US and Egypt. After calibration to the established Turkish foraminifera and nannofossils standard, the palynological analysis shows that the recorded dinoflagellate cysts events (e.g. FO of Labyrinthodinium truncatum, Cerebrocysta poulsenii and Unipontidinium aquaeductus and LO of Palaeocystodinium ventricosum) occurred chronostratigraphically earlier in SE Turkey than in NW Europe and on the East Coast of the US.